page_title: Macroraptorial sperm whale
section_title: Description
hierarchical_section_title: Macroraptorial sperm whale / Description
caption_attribution_description: Italiano: Fossil of Acrophyseter, an extinct sperm whale- Took the photo at De Groene Poort, Boxtel
context_page_description: Macroraptorial sperm whales were highly predatory whales of the sperm whale family of the Miocene epoch that hunted large marine mammals, including other whales, using their large teeth. Likewise, they were all likely the apex predator of their habitats, comparable to the modern day killer whale, and achieved great lengths, with one species–Livyatan–measuring about 13.5–17.5 metres. The macroraptorial sperm whales–Albicetus, Acrophyseter, Brygmophyseter, Livyatan, Scaldicetus, and Zygophyseter–are an informal grouping of genera without a family designation. All species are known by at least a skull.
context_section_description: Macroraptorial sperm whales had large, functional, conical teeth in both jaws, as opposed to the modern sperm whale whose teeth are small and nonfunctional in the upper jaw. The teeth were deeply rooted into the gumline and could interlock, probably to aid in holding struggling prey. The teeth of Livyatan, at a length of 31 cm (12 in), were one of the biggest teeth of any animal, excluding tusks. The macroraptorials also had well-developed muscles used in biting–the temporalis and masseter. They also developed buccal exostoses in the mouth, bony growths which act as buttresses during biting, further increasing the bite force.
  Acrophyseter likely measured 3.9–4.3 m (13–14 ft) in life, Brygmophyseter 7 m (23 ft), Livyatan 13.5 or 17.5 m (44 or 57 ft), and Zygophyseter 6.5–7 m (21–23 ft). The postcranial remains of only Zygophyseter and Brygmophyseter were found. The elongated lumbar vertebrae of Zygophyseter indicate it had larger multifidus and longissimus back muscles and was, thus, faster than the modern sperm whale which, comparable to other large open-ocean animals, travels horizontally at 4 km/h (2.5 mph).
  A characteristic of sperm whales, the macroraptorials had a curved basin–the supracranial basin–on the top of the skull. This encompassed the entire breadth if the snout in Livyatan and Brygmophyseter; Zygophyseter and Acrophyseter, instead, had reduced basins indicating beaks.
caption: Upper and lower tooth rows of Acrophyseter
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